Stand or sit with a dumbbell in each hand and hinge forward at the hips with a neutral spine. With a slight bend in your elbows, lift the weights out to your sides until your arms are in line with your shoulders. Focus on squeezing your shoulder blades together at the top, then lower the dumbbells back down under control. Keep movements smooth and avoid using momentum.
Log your dumbbell reverse fly sets in 1RM.fit and watch your estimated 1RM update automatically as you get stronger.